This research program will address the following goals related to the acquisition of literacy by Spanishspeaking English language learners: determining developmental shifts in precursor and outcome variables related to literacy, sources and effectiveness of positive transfer at different points in development, and expectable long term outcomes; developing methods to enhance vocabulary development across a wide age span; developing more sensitive and appropriate measures of crucial outcomes of interestmvocabulary and reading comprehension; and finally, developing interview and observation protocols as well as assessments to examine the effects of teacher and classroom quality and level of implementation of interventions. The program will build on a prior research program conducted by this team of investigators. Through pursuit of four research subprojects, the investigators will document attainment in English language and literacy skills of ELLs from low-income families based on a longitudinal study (pre-K-6) and examine the effects of home and classroom interventions on the early literacy skills of bilingual kindergarten students. Building on current research that demonstrates the powerful role of vocabulary in predicting reading comprehension, investigators will also focus on methods to enhance vocabulary development among these students and will evaluate the impact of a series of vocabulary interventions with English language learners in grade 1 through 5. The research subprojects will be supported by an Assessment Core that will provide psychometric, methodological, and analytical consistency across the projects and will develop new, more sensitive, more appropriate measures of vocabulary and reading comprehension, a Teacher and Classroom Implementation Core that will develop interview and observation protocols as well as teacher assessments for the research subprojects to use in their studies, and an Administrative Core that will coordinate efforts, exercise quality control, and assist in the dissemination of project results.